Table 2. Binding Energy Values for Compounds 8a, 8b, 12a, and 12b and Standard Ligands with Bacterial Dihydrofolate Reductase and Tyrosyl-tRNA Synthetase Proteins.

	Gibbs free energy (S) (kcal/mol)
sample	bacterial dihydrofolate reductase	bacterial tyrosyl-tRNA synthetase
8a	–40.8	–36
8b	–37.14	–36.6
12a	–39.7	–37.1
12b	–37.9	–40
cocrystallized ligand (standard)	–16.2	–18.6